Examine source code of Open on Spotify button

{
  "name": "__MSG_appName__",
  "description": "__MSG_appDescription__",
  "version": "1.0",
  "manifest_version": 2,
  "short_name": "__MSG_appShortName__",
  "default_locale": "en",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "page_action": {
    "default_icon": {
      "16": "icons/16.png",
      "32": "icons/32.png"
    },
    "default_title": "Open on Spotify"
  },
  "icons": {
    "16": "icons/16.png",
    "32": "icons/32.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1d8377c8-59ba-471d-8335-43bae588b40a}"
    }
  }
}